Matrimony

The matrimonial covenant, by which a man and a woman establish between
themselves a partnership of the whole of life and which is ordered by its
nature to the good of the spouses and the procreation and education of
offspring, has been raised by Christ the Lord to the dignity of a sacrament
between the baptized.[from the Catechism of the Catholic
Church]

Marriage is both a vocation (calling by God) and a sacrament,
which makes it doubly blessed and imparts special graces to aid
couples.

Because of its covenantal nature, marriage is the only
sacrament in which the participants confer it upon each other. In other words,
the couple’s exchange of marital vows bestows the sacrament. The priest or
deacon is still essential. He is the official witness who represents Christ
and the Church.